2020 Web Catalog - Flipbook - Page 500
17 Water Softener Sizing Information
We are now ready to proceed with a typical approach to
selecting a water softener. Information is first gathered on all
of the aspects of the boiler system discussed in this section.
A listing of all our design factors should first be assembled.
The following represents a typical boiler plant from which we
can calculate the demand for a softener.
(1)DETERMINE WATER HARDNESS
Analysis received or taken is in parts per million (PPM).
Convert to grains per gallon (GPG).
342 ÷ 17.1 = 20 GPG.
(2)DETERMINE BOILER HORSEPOWER
Boiler rating is in pounds per hour of steam.
Convert to Horsepower.
3,450 pounds per hour ÷ 34.5 = 100 H.P.
(3)DETERMINE MAXIMUM GALLONS PER HOUR MAKEUP
Boiler rating is 100 horsepower.
Convert H.P. to gallons per hour make-up.
100 H.P. x 4.25 gallons per hour make-up.
(4) DETERMINE AMOUNT OF CONDENSATE RETURNED
TO SYSTEM AND CALCULATE NET MAKE-UP REQUIREMENT
Make-up per hour is 425 gallons.
Condensate returned is 50% or 213 gallons per hour.
425 - 213 = 212 net gallons make-up per hour.
(5) DETERMINE TOTAL DAILY MAKE-UP REQUIREMENTS
212 gallons net make-up per hour.
Boiler system operates 16 hours per day.
2 12 gallons per hr. x 16 hrs. = 3,392 gallons per operating
(6)DETERMINE TOTAL GRAINS OF HARDNESS TO BE
3,392 gallons per day with a hardness of 20 grains per
When sizing water conditioning equipment, the hardness
should be based on compensated hardness. Compensated
hardness takes into consideration minerals and other factors
that will reduce the softening capacity of a softener.
These items cannot be picked up in a standard hardness
test. To arrive at compensated hardness multiple the figure
on the right by the hardness in grains per gallon.
21 - 40
41 - 70
71 - 100
101 - Plus
CONTINUOUS HARDNESS LEAKAGE
in ppm as CaC03
SALT DOSAGE PER CU. FT
*Raw Water TDS as CaCO3
GRAINS PER GAL
Very Hard10.5 or over
1.0 or less
1.0 to 3.5
3.5 to 7.0
7.0 to 10.5
180 or over
Technical & Engineering
3,392 gallons x 20 GPG = 67,840 grains of hardness
needed to be removed daily.
The answer in our sixth step of 67,840 grains of hardness to
be removed daily, brings us to our final approach in selecting a water softener. Due to the nature of the importance of
obtaining soft water for the boiler feed water, we must allow
for a margin of error in our sizing process. This margin is
commonly 15%. Multiplication of the 67,840 grains per day
by 1.15 results in a total removal demand of 78,016 grains
per day needed to be removed.
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17.0 or less
17.1 to 60
60 to 120
120 to 180